Chair iron for tilting seats



May 11, 1948. A. J. RAITCH CHAIR IRON FOR TILTING SEATS Filed June 21, 1943 2 Sheets-Sheet 1 INV ENT OR. AL EXANDER J, 84/ TCH BY ATTORNEY May 11, 1948. A. J. RAITCH CHAIR IRON FOR TILTING SEATS Filed June 21, 1945 2 Sheets-Sheet 2 mum WW EMA J M w w Patenied May 1], i948 FFlCE 2,441,251 CHAIR IRON FOR TILTING sears Alexander J. Raitch, Port Washington, Wis, as-

signor, by mesne assignments, to The Seng Company, Chicago, 111., a corporation of Illinois Application June 21, 1943, Serial No. 491,576

(Cl. ll5577) 9 Claims. 1

This invention relates to improvements in chairs of the type having a tilting seat and back and particularly to the type where the back tilts relative to the seat in synchronization with the tilting of the seat.

One of the objects of the invention is to provide a chair in which the back is automatically readjusted relative to the seat as the angle of tilt of the seat is changed.

Another object of the invention is to provide a chair in which the back may be independently adjustable both vertically and angularly relative to the seat, to establish a basically proper fit, and also automatically tilted relative to the seat as the angle of tilt of the seat is changed.

Another object of the invention is to provide a chair in which the angular relationship between the back and seat is varied as the seat tilts, and the tilting of the seat and changes of such angular relationship are controlled by single adjustable resilient means.

Another object of the invention is to provide a chair in which the movement of the back relative to the seat is accomplished by simple and compact mechanism having few working parts.

A still further object of the invention is to provide a chair in which the back moves relatively to the seat as the seat tilts and where force exerted upon the seat and the back has substantially no efiect in causing the seat to tilt.

The novel features, which are considered characteristic of the invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, in which:

Figure 1 is a sectional view through a chair embodying the invention, and showing the chair seat and support for the back, the section line meandering to show in full relief the bevel gear arrangement,

Figure 2 is a top plan view ofthe chair, embodying the invention, with the seat removed for the sake of clearness.

Referring in greater detail to the drawings, the pedestal P is of customary design and has, centrally located therein, a hub I 0. A vertically adjustable spindle II is carried by the hub I9. Its vertical adjustment is controlled by a conventional capped nut l2.

A head-piece is secured to and carried by the spindle H. This head-piece comprises a metal base plate i3 and a support member. The metal base plate l3 has an aperture into which the spindle ll tightly fits. The spindle and base plate are held in fixed relationship by riveting over the top of the spindle or securing it by a weld. The support member is riveted to the base plate I3. It comprises spaced vertical side arms M, spring tension rod carrying lug l5, and forwardly projecting seat carrying arms [6, preferably formed from heavy sheet metal with the vertical side arms I l and rod carrying lug l5 bent to the positions shown. The seat carrying arms l6. are held to the vertical side arms M by being riveted or welded thereto. They are set at a slight upward slope relative to the horizontal for the purpose of permitting the seat S to have sufiicient space for backward tilting. The front ends of the'seat carrying arms 16 are held apart by a spaced tube I1. Each arm l6 at its front end has a bronze bearing l9 press fitted into a hole therein. The bearings l9 have extended portions which provide a spacer between the arms l6 and the spider.

The seat carrying spider comprises two spaced arms E8 of customary design. The arms I8 are held in proper spaced relationship to each other and to the arms is by a pin 29. The pin 20 is held in apertures provided in the vertical walls of the arms l8. Fibre spacer washers 2| are inserted between the bearings l9 and the arms I8. The pin 2!] passes through the bearings l9 and spacer tube H to form the pivot for the spider. The arms I?) are provided with apertures 22 in their ends through which screws are inserted into the seat S to hold the same in place. The seat S of conventional design is shown diagrammatically only. The seat supporting spider and the seat S supported thereby are thus tiltable about the pivot 20.

A bell crank designated generally at 23 is pivotally carried by the head-piece. The bell crank 23 is preferably a casting and has two spaced axially aligned bosses into which are fitted bronze bearings 25. A pin 2t is carried by the side arms l6 and passes through the bearings 25 to form the pivot for the bell crank 23. The bell crank 23 may be spaced within the vertical side arms M by spacing washers 25 riding on the pivot pin 24. A vertically depending arm 2i, of the bell crank 23, is provided with a forwardly projecting knife edge 28 which has a centrally located slot straddling the spring tension rod 30. The horizontal leg 29 of the bell crank 23 has two downwardly depending spaced bosses into which are fitted bronze bearings 29m. The vertical and horizontal legs 2'! and 29 of the bell crank 23 are reinforced by flanges located along the edges of the bell crank 23 and merging into the bosses containing the bearings 25 and by a centrally located flange.

The bell crank 23 is urged in clockwise direction about the pivot M by a compression spring 33. The outer end of the spring 33 is contained in a spring cup 32 against which bears an adjustable hand wheel 3| having a threaded interconnection with the spring tension rod 38. The rod-3fl passes through the central portion of the spring and has its inner and squared end headed to hold the same against rotation in the carryme lug 15 of the support member. A spring cup 38 slides along the rod 39 and bears against the inner end of the spring 33. Its rear surface is notched to provide a bearing between it and the knife edge 28. The pressure of the spring may be in creased by screwing down on the hand wheel 3 I. This increases the resistance of the spring to any counter-clockwise motion of the bell crank 23. It is preferable to insert felt buffer pads l 511 between the depending arm 27 and the lug it, which. lug. acts as an abutment against which the arm 2.1 of the bell crank 23 rests in the normal position, to cushion the action of the bell crank.

The arms 18 of the seat-carrying spider are provided with aligned apertures in which is fixedly carried a pivot pin 35a. The pin is located as viewed in Figure 1, to the left of the bearings 29a carried in the horizontal arm 29. A connector link, or oscillating member designated generally at 35, forms a connection between the spider and the bell crank 23. The connector link 35, as viewed in Figure 1, has its forward endprovided at each side with bosses. Each boss is provided with a bronze bearing 35b through which the pin 35a passes to form the pivot between the spider and the connector link 35, and with apertures through which passes a pin 29b. The pin 2% likewise passes through the bronze bearings 29a in the horizontal arm 29 of the bell crank 23, to form the pivot between the connector link 35 and the bell crank 23. The horizontalarm 29 thus forms a lever cooperating with the link 35.

The working length of arm 29 of the bell crank 23 is the distance from the center of pin 24 to the center of pin 29a, and is less than onethird of the distance between the pin 35a and angular movement of the connector link 35 with respect to the spider or seat.

Use is made of this angular movement of the connector link 35 to accomplish a synchronization between the tilting of the seat S and the tilting of the back B relative thereto. The connector link 35 is provided with a rearwardly extending back supporting member 36 with respect to which the link 35 acts as a short lever arm. The member 36 terminates in spaced bosses which provide a bearing support for a supporting bracket 38. A pin 31, carried by the member 38, rotates in these bosses to form a pivotal connection between the member 36 and the bracket 38. The under portion of the member 36 is provided with flanges which support a bevel gear assembly designated generally at 4| of conventional design. The bracket 38 has a customary vertical adjustment designated generally at 39 by which a curved plate 40, carrying the back B, may be adjusted vertically within a predetermined range. The lower portion of the vertical adjustment device 39 is secured by flexible coupling means to the bevel gear assembly. The operation of the bevel gear assembly 4-], therefore, swings about the pivot 31, the back supporting bracket 38 and vertical adjustment 3!) carried thereby. With the seat in a normal position, the back can be independently adjusted angularly and vertically relatively to the seat to arrive at a basically proper fit.

As the seat is tilted counter-clockwise, as viewed in Figure 1, to the position shown in the dotted lines approximately 9 degrees below its normal position, the connector link 35 will be swung counter-clockwise about the pivot 35a so that it and its integral rearwardly extending back supporting member 36 assume the position shown in the dotted lines in Figure 1. Under these conditions the link 35 and its integral back supporting extension 36 function, in eilect, as a rock lever pivoted at 35a. This pivot motion is arrested by felt cushioning pads 15b engaging with arm 29. In the particular angular basic adjustment shown, the back forms, with respect to the level of the seat, an angle of approximately 88 degrees. However, as the connector link 35 is swung to the dotted position, this angle increases to approximately 103 degrees. Thus from the normal position to the fully tilted position of the seat, the angle between the seat and the back opens approximately 15 degrees. The increase in this angular relationship takes place gradually, and the motion of the backrelative to the seat is smooth and synchronized with the motion of the seat. Thus the device automatically accomplishes the easing of the back pressure against the person sitting in the chair as theseat is tilted backward by the changing of theposture of the body.. This greatly increases the comfort and posture fit of the chair.

In the normal position of the seat, as viewed in Figure 1, the pin 24 lies slightly above the. imaginary lines drawn from the pin 29 to the pin 291). This relationship accomplishes a specific function. If force is exerted upwardly upon the seat and the back, such force, when resolved to its turning moment on the connector link 35 will have substantially no force effective to cause the seat to tilt upwardly about the pivot 26. This characteristic is advantageous in that a substantially lighter compression spring may be utilized than would be the case if such force had any substantial tendency to cause the seat to tilt upwardly. The seat (constructed as herein taught) is tilted merely by the balancing of the weight of the person seated therein and not by any force acting upon the seat and the back. This relationship also permits the use of a single adjustment compression spring to accomplish resistance to tilting and proper synchronization between seat and back.

Although there is shown and described a certain specific embodiment of the invention; many modifications thereof are possible. The invention is not to be restricted except insofar as necessitated by'the prior art and by the spirit of the appended claims.

Iclaim:

q 1. In a chair, a seat support, a tiltable seat pivotally mounted on the seat support, means for resisting tilting said seat in one direction including a bell crank pivotally mounted on the said support, a connector link operatively connected between said seat and one arm of said bell crank. and resilient means bearing upon the other arm of the bell crank, saidlink havin angular movement with respect to said seat when said seat and bell crank are simultaneously moved by the tilting of said seat, a back supporting member rigidly secured to said connector link a back supported by said back supporting member whereby the back receives its angular movement from said link, and means for selectively varying both the vertical and the angular adjustment of the back with respect to the back supporting member.

2. In a chair, a, seat support, a pivoted seat mounted on the seat support, a bell crank pivotally mounted on the seat support, spring means engaging one arm of the bell crank for urging said bell crank in one direction, an oscillating member operatively connected between the other arm of said bell crank and said seat, said member having angular movement with respect to said seat when said seat and bell crank are simultaneously moved by the pivoting of said seat, a back supporting member rigidly secured to said oscillating member, and a back supported by said back supporting member whereby the back receives its angular movement from said oscillating member.

3. In a chair, a head-piece, a seat, a pivotal connection between said seat and said head-piece, a bell crank having a first arm adapted to be operated by resilient means and a second arm adapted to be operated by said seat, resilient means acting upon said first arm and said headpiece, a pivotal connection between said bell crank and said head-piece, a connector link, a, pivotal connection between said link and said seat, a pivotal connection between said link and said second arm, and a back supported for movement by and in the same angular direction as and with said link.

4. In a chair, a head-piece provided with front and rear pivotal points, a seat supporting spider having front and rear pivotal points, a pivotal connection between the front pivotal point of said spider and the front pivotal point of said head-piece, a bell crank having a first arm adapted to be operated by a compressible spring and a second arm adapted to be operated by said spider, a compressible spring acting upon said first arm and said head-piece, a pivotal connection between said bell crank and the rear pivotal point of said head-piece, a connector link having spaced pivotal points, a pivotal connection between the rear pivotal point of said spider and one of the pivotal points of said link, a pivotal connection between the other pivotal point of said link and said second arm, said link being provided with an extension member, and a back supported for movement by and in the same angular direction as and with said link.

5. In a chair, a head-piece provided with front and rear pivotal points, a seat pivotally connected to said front pivotal point, a bell crank pivoted to said rear pivotal point, a connector link pivotally connected to said seat and said bell crank, resilient means acting upon said head-piece and said bell crank to urge said seat to normal position, the pivotal connection between said bell crank and said rear pivotal point lying within the confines of lines extending from said front pivotal point to the respective pivot points of said connector link to said seat and said bell crank, and a back supported for movement by and in the same angular direction as and with said link.

6. In a chair, a seat support, a pivoted seat mounted on the support, means for urging said seat to normal position including a bell crank mounted on the seat support, yieldable means bearing on one arm of said bell crank, and a connector link operatively connected to the other arm of thebell crank and to the seat, said connector link having angular movement with re- &

spect to said seat as said seat and bell crank are simultaneously moved by the pivoting of said seat, said link being provided with a fixed extension member, and a back supported by said extension member to receive the angular movement of said link.

7. In a chair, a seat support, a seat pivotally mounted on said support, a bell crank pivotally mounted on said seat support rearwardly of the pivotal mounting for said seat and having a spring compressing arm and a connector arm, spring means acting on said spring compressing arm, a connector link pivotally connected to and extending between the underside of said seat and said connector arm, said link including a back supporting extension disposed beneath the seat and extending rearwardly of the pivotal connection between the link and seat towards the rear edge of the seat, the working length of saidconnector arm being less than one-third of the distance between the pivot point of said seat and the pivotal connection between said link and seat, and a back supported for movement by and in the same angular direction as and with the back supporting extension of said link.

8. In a chair, a, head-piece, a seat having a pivotal connection to said head-piece, back supporting means pivotally supported on said seat at a point spaced from the rear of said seat a distance substantially equal to one-third the length of said seat, a back carried on said; back supporting means, a bell crank carried by said head-piece and having one arm pivotally connected to said back supporting means at a point spaced from the pivotal connection betweensaid back supporting means and said seat whereby tilting movement of said seat is transmitted to said bell crank and simultaneously causes said back supporting means to pivot relative to the seat, and resilient means acting upon the other arm of said bell crank and said head-piece.

9. A tilting mechanism for the seat and back of a chair, comprising: a head piece; a spider pivoted by its forward end portion on said head piece; a back supporting member pivoted on said spider behind said head piece, said member being provided with a short forwardly extending lever arm; a bell crank pivoted on said head pie 0a,; said bell crank having one of its arms pivotally,

secured to said lever arm at a point spaced from the pivotal connection of the back supporting member on the spider and having its other arm normally pressed against an abutment which limits rotation of said bell crank in one direction,

and resilient means urging said other arm against said abutment. ALEXANDER J. RAI'I'CH.

CKTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 180,548 Chichester Aug. 1, 1876 647,178 Chichester Apr. 10, 1900 1,346,110 Atwood July 13, 1920 1,501,180 Peters et a1 July 15, 1924 1,909,018 Senpiel May 16, 1933 1,986,105 Foote Jan. 1, 1935 2,097,618 Drake Nov. 2, 1937 2,122,565 Foote July 5, 1938 2,321,385 Herold June 8, 1943 2,341,124 Sheldrick Feb. 8, 1944 2,363,935

Boerner Nov. 28, 1944 

